1. Field of the Invention
The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus having a structure designed in such a way that a cleaner blade and a seal disposed for scraping out, removing and recovering toner remaining on the surface of an image carrier is separated from the surface of the image carrier.
2. Related Art
An electrophotographic image forming apparatus in which an electrostatic latent image based on image data is formed by irradiating the surface of an image carrier manufactured by a photosensitive member has been hitherto known. In the image forming apparatus, the electrostatic latent image is developed by a developing device so that a toner image is formed on the surface of the image carrier and transferred to a recording medium such as paper to obtain an image.
Such an image forming apparatus comprises: a first image carrier on which an electrostatic latent image is formed and capable of carrying a toner image obtained by developing the electrostatic latent image; and a second image carrier provided at an intermediate position between the first image carrier and a transfer position where the toner image is transferred to the recording medium, so that the toner image on the surface of the first image carrier is received thereon (primarily transferred), and is then secondarily transferred on the recording medium. In this case, for instance, the toner image composed of various colors of the toner formed on the surface of the first image carrier is superposed on the surface of the second image carrier so that a desired toner image such as a color image can be formed. After that, the toner image is transferred to the recording medium such as paper from the surface of the second image carrier, so that a final image can be obtained.
As described above, in the image forming apparatus provided with the second image carrier, the toner remaining on the surface thereof is removed and recovered for each transfer operation of the toner image on the surfaces of the first and second image carriers to ensure the quality of the electrostatic latent image or the toner image.
Since the toner image obtained by developing the electrostatic latent image is then transferred on the surface of the first image carrier, a cleaner blade and a sealing member for removing and recovering the residual toner are disposed in a state that the cleaner and the sealing member always comes into slide contact with the surface of the first image carrier. However, on the surface of the second image carrier, for instance, when the color image is formed, the toner images are superposed on the surface of the second image carrier, and then, transferred to the recording medium.
Accordingly, as shown in FIG. 21, a cleaner blade 522 or a sealing member 523 in a state that is separated from the surface of a second image carrier 516 is pivoted in the direction of an arrow mark as required to come into slide contact with the surface of the second image carrier so as to scrape out toner remaining on the surface of the second image carrier 516 in a cleaner housing 563 in the direction shown by an arrow mark of a dashed line, so that the removed toner is recovered. A member 553 is a roller that rotates the second image carrier 516 and serves as a backup member of the cleaner blade 522 or the sealing member 523. Such a structure is disclosed in Japanese Patent Publication Nos. 2004-157285A (JP-A-2004-157285) and 7-121037A (JP-A-7-121037), for instance.
In such a structure, when the cleaner blade 522 comes into slide contact with the surface of the second image carrier 516 to scrape out the residual toner, the toner to be removed and recovered temporarily lifts in the cleaner housing 563, what is called a toner cloud is generated. The toner cloud is floating toner, and falls and settles after a certain time period elapses. Therefore, when an image forming operation is carried out at a usual speed or so, even if the cleaner blade 522 or the sealing member 523 is separated from the surface of the second image carrier 516, the floating toner is settled until the cleaner blade or the sealing member is separated from the surface of the image carrier so that the floating toner hardly leaks outside the cleaner housing 563 as a closed space.
However, with a high-speed operation of an image formation in recent years, as a time period during which the cleaner blade 522 or the sealing member 523 is separated from the surface of the second image carrier 516, a sufficient time necessary for settling the toner cloud is hardly ensured. Namely, there is an anxious that the cleaner blade 522 or the sealing member 523 is separated from the surface of the second image carrier 516 before the toner cloud is settled to open the closed space, and accordingly, the floating toner leaks outside the cleaner housing 563 to contaminate a neighborhood therewith. For instance, when the cleaner blade 522 or the sealing member 523 is pivoted so as to be separated from the surface of the second image carrier 516, pressure instantaneously rises in the cleaner housing to generate an air flow jetted to an outer part. Thus, the floating toner may possibly leak outside the cleaner housing 563. Accordingly, the toner that does not originally exist in the toner image formed on the first and second image carriers is mixed and its color is mixed, so that the quality of the image is deteriorated or the floating toner leaking in an apparatus main body is accumulated in a periphery member to contaminate a periphery therewith. Thus, a maintenance work is difficult. Further, when a detector, what is called a patch sensor disposed to maintain the high quality of the image and detect the density of the toner image, is contaminated, the quality of the image is deteriorated.